Unexpected NPE during the test.
How to reproduce:
1) Run the test from Comments (I belive the test may be easily reduced) on Windows2000 with JDK6.0b45 (or b40). You would see a frame with JTable in it.
2) Press left mouse button on the bottom of the frame and drag mouse up on the screen till the frame become a title. You should do it fast enough may be for several times.
3) You may also see an Exception if drag top border of the frame.
The exception is:
Exception occurred during event dispatching:

java.lang.NullPointerException
at java.awt.Component$BltBufferStrategy.revalidate(Component.java:3933)
at java.awt.Component$BltSubRegionBufferStrategy.validateAndShow(Component.java:4025)
at javax.swing.BufferStrategyPaintManager.show(BufferStrategyPaintManager.java:243)
at javax.swing.RepaintManager.show(RepaintManager.java:1109)
at javax.swing.SwingPaintEventDispatcher.createPaintEvent(SwingPaintEventDispatcher.java:43)
at sun.awt.windows.WComponentPeer.postPaintIfNecessary(WComponentPeer.java:641)
at sun.awt.windows.WComponentPeer.handleExpose(WComponentPeer.java:625)
at sun.awt.windows.WToolkit.eventLoop(Native Method)
at sun.awt.windows.WToolkit.run(WToolkit.java:277)
at java.lang.Thread.run(Thread.java:608)

Seems this exception doesn't occur with pure AWT testcase.